Rain-water is for cooking purposes, as for other purposes, the best, but
is seldom used, especially in large cities, where it is difficult to
procure it. Another difficulty is, when procured it soon gets foul.
The next best is river-water, or water from lakes.
By boiling, water evaporates its gases and alkali, and is inferior
afterward for cooking purposes, especially for boiling vegetables;
therefore, we earnestly recommend to use the water at the first boiling.
When foul water has to be used for want of other, if no filter,
charcoal, sand, or paper can be had to filter it, it will improve by
boiling it and then exposing it to the air for some time.